Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: fishkiller on February 24, 2013, 09:30:50 PM
-
hello,I need a little help....ok...a LOT of help. Doing the math for my steps per unit, I come up with 20000. But when I calibrate the axis, it changes it to like 150000. but if i set the motors to this 150,000 then the motors stall. why?
-
I have my micro-stepping set at 10,200 steps per revolution on the motors, 1 to 1 for gear ratio, 10 revolution per unit.
-
given your numbers, 10,200 microsteps at direct drive,* 10 per unit =102,000
Give that a try
John
Ps, do you really need that high a microstep? I understand, correct me someone if I got it wrong but anything over 10 is ineffectual
-
microstep is 10. steppers are 200 steps per rev. 1 to 1 gear ratio. and 10 tpi
-
Try this calculator, it may help.
http://www.machsupport.com/forum/index.php/topic,16315.0.html
-
If I had read your figures correctly - 200 steps x 10 micro = 2000 steps per rpm.
2000 x 10 tpi = 20,000 steps per inch
At 150,000 - your motors would be trying to spin so slow that they mayappear to be stalled.
Under motor tuning and setup, I would try for each axis as an example -
steps per (20,000)
Inches per minute (12)
Acceleration inches per sec/sec (1)
That should give you the correct steps per - then adjust speed and acceleration to suit the materials you are working with. I work in metric so this is just a best guess from me.
Regards, Danny.
-
i can get good movement out of the motors,nice and smooth, when i put in 20000. but when i calibrate the axis in settings,it sets the steps per so much higher. if i calibrate again it stalls the motors and wont repeat the calibration. is there another way to calibrate the axis so the DRO's read correct? I have been watching videos and reading tutorials so much, i may be over thinking.
-
I much prefer calculating the steps per unit, doing so ensures they will be as accurate as your hardware. Using the calibration is only as accurate as your measuring which is unlikely to be as accurate as the hardware.
Hood
-
i measure the movement with a dial indicator. if i calibrate the motor in the settings menu, it changes the steps to 150,000 steps per unit. the DRO seems to read correct. But doesnt seem right.
-
The DRO on the Mach program is only correct because it's calibrated by the figures you input it the motor tuning menu. As long as your figures of 10 microsteps x 200 steps per rpm are correct - then a motor will require 2000 steps per rpm - so 2000 steps per revolution x 10 TPI (or 10 revolutions for one inch of travel) = 20,000 steps for your motor to move your axis one inch.
When you input say, 20,000 then use the calibration function in settings and ask it to move an axis one inch - how far does the axis actually move?
Can work a lot out from that. Danny.
-
i am following ya. when i input the 20,000 into my motor tuning, the DRO moves , but not correct. for instance, if i move x-axis 3 inches ,the DRO will read 20. As if the units were in mm instead of inches. Double checked that. The only way for me to get the DRO to read somewhat correct is to calibrate and allow it to change the motor setting to its new value.
-
This should be an easy entry. The math is straight forward. Before i installed the acme thread, i bench tested for accuracy. 10 revs per inch. motors coupled direct...
-
With the dial indicator, with the motors set at 20,000 steps per inch, the axis will move .085
-
Attach your xml and I will have a look.
Hood
-
In that case, 0.85 at 20,000 steps says to me you need to input 23,530 instead of 20,000. Give that figure a try and see if it gives you 1 inch of travel.
Danny.
-
Just wondering if your machine is 12 tpi and not 10 tpi.
At 12 tpi, 24000 should be the correct steps per. Backlash may account for the 470 difference in my figure of 23530 to being 24000.
Danny.
-
i just reloaded mach3. DRO seem to read correct now. not exactly, but looks to be only .100 of on y axis and .25 off on the x axis. the x axis is slaved. All the motor settings are the same. Z axis is only .005 off.
I will get my xml sent to you as soon as i can Hood. Thanks for all the help. I am new to this, but am confident I can overcome
-
I believe I have solved the problem. I uninstalled and reinstalled mach3. Then input 20,000 steps into motor tuning. Then took sonicracings advice and set velocity and acceleration very low. I have some backlash, and have parts on the way for that. I made the first cut, and have minor issues.
I built my machine on a budget,and went over...oops. There is things i would have done different, but am satisfied for now.
Thanks for the support from evryone in this forum. You guys are great.